In the related art, a technology for detecting weight on soles has been proposed. For example, PTL 1 discloses a foot force sensor including at least two pockets which may be inflated with air or filled with liquid to measure the air or liquid pressure within each pocket using a pressure sensor. The foot force sensor may be formed as an insole worn inside a shoe, for example. The foot force sensor is capable of detecting weight on a sole of a user wearing the shoe with the insole.